First, you have to look at whether the project was an "improvement" or a "repair," which based on the information you provided, it sounds like it was a 'capital improvement.'
Lawn care and repairs and maintenance are expensed because these costs keep the property in it's original condition. Improvements distinguish themselves because they add value to the property and must be "capitalized" and then you take depreciation. For more info on this difference, this article is providing a good summary HERE.
It sounds like you should add the landscaping project as an asset, within the rental property and take depreciation. You'll might be able to choose to take special depreciation or section 179 depreciation and deduct the amount in full (or choose to deduct it over the useful life).
